Grinding wheel guard with energy absorbing apparatus

ABSTRACT

A grinding wheel energy absorbing apparatus wherein a grinding machine wheelhead carries both a grinding wheel within a grinding wheelguard and the grinding machine base is fitted with a rail and the grinding machine wheelguard is fitted with an extruder plate having uniquely configured extruder holes therethrough, and an extrudable jerk block is disposed between the rail and the extruder plate, such that during the grinding wheel breakage, relative movement of the wheelguard to the machine base causes the extrudable jerk block to be forced through the extruder plate and energy is thereby absorbed.

United States Patent Matson Sept. 2, 1975 GRINDING WHEEL GUARD WITHENERGY ABSORBING APPARATUS [75] Inventor: Charles Bernard Matson,

Cincinnati, Ohio [73] Assignee: Cincinnati Milacron, Inc.,

Cincinnati, Ohio [22] Filed: Aug. 30, 1974 [21] Appl. No.: 502,005

[52] US. Cl 51/269; 51/269 [51] Int. Cl. B24B 55/04 [58] Field of Search51/268, 269; 144/251 [56] References Cited UNITED STATES PATENTS3,571,983 3/1971 Stewart 51/269 3,690,074 9/1972 Mrugala 51/2693,694,971 10/1972 Renner 51/269 X Primary Examiner-A1 Lawrence SmithAssistant ExaminerNicholas P. Godici [57] ABSTRACT A grinding wheelenergy absorbing apparatus wherein a grinding machine wheelhead carriesboth a grinding wheel within a grinding wheelguard and the grindingmachine base is fitted with a rail and the grinding machine wheelguardis fitted with an extruder plate having uniquely configured extruderholes therethrough, and an extrudable jerk block is disposed between therail and the extruder plate, such that during the grinding wheelbreakage, relative movement of the wheelguard to the machine base causesthe extrudable jerk block to be forced through the extruder plate andenergy is thereby absorbed.

2 Claims, 6 Drawing Figures GRINDING WHEEL GUARD WITH ENERGY ABSORBINGAPPARATUS BACKGROUND OF THE INVENTION In the art of grinding machines,increasing energy levels have been reached by the grinding wheels forthe high speed production of parts. It has become impera tive,therefore, to find new and better ways to control the high energyfragments created when a grinding wheel breaks. Initially, only metalgrinding wheelguards were provided around a grinding wheel to containbroken wheel fragments. In time, however, as energy levels increased,wheel fragments have obtained greater mobility during a wheel breakageand have made their way out of the openings which exist in a wheelguard.Also, wheel fragments tend to react against, and ricochet from, therigid structure of the wheelguard. It, therefore, became preeminent todevelop means for absorbing the energy which exists in the discretewheel fragments of a broken wheel assembly and one such prior artdevice, which has proved extremely useful, is that of the guard systemof US. Pat. No. 3,571,983 of Stewart et al, assigned to the assignee ofthe present invention.

In the Stewart patent a polyurethane foam liner, molded to thecircumference of a grinding wheel, has been secured within a metalgrinding wheelguard and comprises a closed cell frangible element whichwill deform upon impact of a grinding wheel fragment and thus absorbkinetic energy of the moving body.

The principle applied in the Stewart patent of entrapping the wheelfragments in crushed foam liners has proved to bev a very useful energyabsorbing device. However, it does have to be custom-molded to a givenwheel size and thus is unique to each assembly.

The desirability may be seen of having an easily manufactured, highenergy absorbing device, which may generally be applied to grinderswithout regard to the configuration of the wheel except as to energycontent. Therefore, the problems inherent in prior art devices have beenobviated in a novel manner by the within invention which may be used asa sole means for absorbing kinetic energy of a brokengrinding wheel or,alternatively, may be used in conjunction with several other prior artenergy absorbers.

It is, therefore, an object of the present invention to provide aneasily manufactured and easily applied device for absorbing the kineticenergy of a broken grinding wheel.

Another object of the within invention is to provide a device which iscapable of absorbing high energy levels of a broken grinding wheel.

Still another object of the present invention is to provide an apparatuswhich may be easily varied as to its capability or absorbing forces overa given period of time.

SUMMARY OF THE INVENTION This invention relates to grinding machineshaving a rotatably mounted grinding wheel capable of generatingrelatively high kinetic energy.

A wheelhead is carried on the grinding machine which carries a rotatablymounted grinding wheel within a grinding wheelguard, and a catch rail isprovided on the base of the machine while an extruder plate is securedto the machine wheelguard and has therein specially configured extrudingholes. A block made of extrudable material, such as lead or any otherreadily extrudable material, is interposed between the stationary catchrail on the base and the extruder plate on the wheelguard. At the timeof wheel breakage, the wheelguard undergoes movement relative to themachine wheelhead and thus causes the extrudable material to becompressed and flowed through the extruder plate holes, and the energyexpended to extrude the material through the extruder plate is providedby the kinetic energy of the broken wheel fragments.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation of a grindingmachine wheelguard and energy absorbing assembly.

FIG. 2 is an enlarged section taken through a grinding wheel energyabsorbing apparatus along the line 22 of FIG. 1.

FIG. 3 is a section taken through a grinding wheel energy absorbingapparatus illustrating extrudable material, extruder plate, andstationary rail, taken along the line 3-3 of FIG. 2.

FIG. 4 is a side elevation of a grinding machine wheel and wheelguard ata position just after wheel breakage.

FIG. 5 is a section through a grinding wheel energy absorbing apparatusof FIG. 2 at a point just after wheel breakage.

FIG. 6 illustrates successive stages of extrusion of extrudable materialthrough a specially configured orificc.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, FIG.1 discloses a side elevation of a grinding machine wheelguard assembly10. A wheelhead 11 is slidably maintained on ways 12 on the machine base13 to advance and retract the wheelhead 11 when performing grindingoperations. A grinding wheel 14 is rotatably carried in the wheelheadand possesses a relatively high degree of kinetic energy due to itsrotating mass.

The wheelguard assembly 10 is carried on the wheelhead 11 by bolts 15 inclearance holes 16 so the wheelguard may rotate relative to the wheelcenter. The wheelguard 17 provides a shroud for enclosing the majorityof the periphery 18 of the grinding wheel 14, and the assembly 10 haslocated within it a polyurethane foam liner 19 such as disclosed in U.S.Pat. No. 3,571,983 of Stewart, et al which provides a frangible elementcapable of being crushed and thereby absorbing energy of broken wheelfragments. A base member 20 carries wheelhead 11 in the slidable vectoron ways 12.

An energy absorbing device .21 is shown having the basic elementscomprising a catch rail 22 secured to the base member 13 between thewheelguard 17 and the base member 13; an extruder plate 23 secured tothe wheelguard l7 and extending between the wheelguard 17 and the basemember 13; and ajerk block 24 situated on the extruder plate 23 betweenthe extruder plate 23 and the catch rail 22.

FIG. 3 is a section through the energy absorbing device 21 depicting thecatch rail 22, extruder plate 23, and jerk block 24. The catch rail 22comprises a rigid bar structure secured by screws 25 to base member 13.The extruder plate 23 comprises a plate structure having a plurality ofcompartments 26 formed along its plate surface 27 by a plurality ofribs, or gussets" 28, and orifices 29 are provided through the floorsurfaces 30 of the compartments 26. The gussets 28 add strength to theplate 23 and further provide side support to the jerk block 24 containedwith the compartment 26 so that when an extrusion process has begun,

the jerk block material 31 will be channeled into the extruder orifices29. The orifices 29 shown are conical holes, which will give anon-linear energy absorbtion characteristic in the early stages ofextrusion, but the orifices 29 may be configured to any shape desired orto any number needed, to otherwise vary the energy absorptioncapabilities. The jerk block 24, comprised of extrudable material, suchas lead for example, rests on the floors 30 of r the compartments 26 andis designed to touch the catch rail '22 in its normal, uncxtrudcd state.Clearance reliefs 32 have been provided in the jerk block 24 to straddlethe gussets 28 of the extruder plate 23, and the material'31 may bemanufactured as one unit as shown, or shaped into discrete jerk blocks24 for each compartment 26.

The section shown in FIG. 2 illustrates the catch rail 22 and one of itsrespective clamping screws securing it to the base member 13. Further,the extruder plate 23 is shown fused at several points 40 to the machinewheelguard 17, but it may be secured to the wheelguard 17 by any otherconventional means desired. The jerk block 24 is shown resting on thefloor of the extruder plate compartment 26 and the gusset 28 andclearance relief 32 in the jerk block 24 is illustrated. The top surface33 of the jerk block 24 is beveled off at a slope corresponding to asurface 34 on the catch rail 22 to assist in capturing the jerk block 24when relative movement is begun by the extruder plate 23 towardsthecatch rail 22.

The assembly 10- depicted assumes that the wheel 14 is traveling in acounterclockwise direction when the energy absorbing device 21 isapplied as shown in FIG. 1. However, the energy absorbing device 21 maybe applied to any structure which has the device 21 mounted in such amanner that the extruder plate 23 moves toward the catchrail 22' when awheel breakage occurs.

FIG. 4 illustrates the assembly of FIG. 1 just after wheel breakage hasbegun. The high energy wheel fragments 35 are shown imbedded in thepolyurethane liner l9 and further are shown to have caused thewheelguard 17 to rotate about the wheel spindle axis 36 relative to thewheclhead 11. This relative rotational movement of the wheelguard 11causes a lifting of the extruder plate 23 towards the catch rail 22which is prevented from movement in the vertical direction by the basemember 13. The jerk block 24 has been deformed at several points 37 andhas a portion 38 cxtr 'udcd through plate orifice 29.

FIG. 5 depicts an enlarged view of the energy absorbing device 21 justafter wheel breakage, illustrating that the extruder plate 23 has movedup towards the catch rail 22 and the jerk block 24 has been deformed atcertain points 37 and has a portion 38 extruded through the extruderplate orifice 29.

Successive stages of extrusion of the jerk block material 31 through theextruder plate orifice 29 are shown in FIG. 6 at various points in time.The tapered orifice 29 chosen for this example requires variable forcesover uniform time increments to push the extrudable material 31 throughthe successively decreasing diameter of the orifice 29 until theextrudable material 31 has passed entirely through the extruder plate23. Thereafter, the force remains constant since it is seen that theextruded portion slug 38, extending below the extruder plate 23 has aconstant shaped diameter and has reached a steady state energy absorbingmode.

I claim:

1. In a grinding machine having a movable wheclhead wherein saidwheclhead carrys both a rotatably mounted grinding wheel and a grindingwheel guard, an apparatus for absorbing energy of a grinding wheelcomprising:

a. a base;

b. a catch rail secured to said base;

c. an extruder plate, secured to the machine wheel guard and adapted formovement with said wheel guard relative to said catch rail, wherein saidextruder plate has a generally rectangular shape of plate surface, witha plurality of compartments serially formed along its surface bygussets, and further wherein the floors of said compartments have aplurality of extruder orifices therethrough; and

d. a jerk block, comprised of extrudable material and received betweensaid catch rail and said extruder plate.

2. The apparatus of claim 1, wherein said jerk block is of a rectangularlength profile, having a generally square crosssection, and further,having a plurality of transverse reliefs along its length correspondingto the spacing of said gussets so that non-relieved areas of said jerkblock may engage said compartment floors

1. In a grinding machine having a movable wheelhead wherein saidwheelhead carrys both a rotatably mounted grinding wheel and a grindingwheel guard, an apparatus for absorbing energy of a grinding wheelcomprising: a. a base; b. a catch rail secured to said base; c. anextruder plate, secured to the machine wheel guard and adapted formovement with said wheel guard relative to said catch rail, wherein saidextruder plate has a generally rectangular shape of plate surface, witha plurality of compartments serially formed along its surface bygussets, and further wherein the floors of said compartments have aplurality of extruder orifices therethrough; and d. a jerk block,comprised of extrudable material and received between said catch railand said extruder plate.
 2. The apparatus of claim 1, wherein said jerkblock is of a rectangular length pRofile, having a generally squarecross section, and further, having a plurality of transverse reliefsalong its length corresponding to the spacing of said gussets so thatnon-relieved areas of said jerk block may engage said compartmentfloors.